Regenerating Life

Abstract

Stem cells, which are ‘immortal’ cells that divide indefinitely and produce many different cell types, are central to how our body develops and maintains itself. Embryonic stem cells can give rise to all cell types in the body, and there has been lots of interest since their discovery in the 1980s in using such cells to generate new tissues or organs to replace diseased or faulty ones. More recently has come the discovery of induced pluripotent stem cells, which are normal skin cells taken from a person and genetically modified or tweaked chemically to give them stem cell properties. There is now hope that both of these types of stem cells might be used in ‘regenerative’ medicine, for instance in producing pancreatic cells that secrete insulin which could be used to treat diabetes. Perhaps the most remarkable breakthrough in recent years has been the discovery that stem cells introduced into a 3D matrix that is infused with chemicals that stimulate the development of particular cell types, can spontaneously form ‘organoids’, which have many of the cell types and even structural features of human organs such as hearts, kidneys, intestines, and even eyes and brains. Organoids make it possible to study how human organs develop but also this area of science raises many ethical issues. For instance, currently human brain organoids can only grow to the size of an embryonic brain, but if in the future they could be induced to grow to adult brain size, could they develop feelings and thoughts?